**https://doi.org/10.26637/MJM0601/0008**

**Exact solutions for linear systems of local fractional**

**partial differential equations**

### Djelloul Ziane

1### , Mountassir Hamdi Cherif

2### * and Kacem Belghaba

3**Abstract**

The basic motivation of the present study is to apply the local fractional Sumudu decomposition method to solve linear system of local fractional partial differential equations. The local fractional Sumudu decomposition methodl (LFSDM) can easily be applied to many problems and it’s capable of reducing the size of computational work to find non-differentiable solutions for similar problems. Some illustrative examples are given, revealing the effectiveness and convenience of this method.

**Keywords**

Local fractional derivative operator, local fractional Sumudu decomposition method, linear systems of local fractional partial differential equations.

**AMS Subject Classification**
44A05, 26A33, 44A20, 34K37.

1,2,3_{Laboratory of mathematics and its applications (LAMAP), University of Oran1 Ahmed Ben Bella, Oran, 31000, Algeria.}

***Corresponding author**:1djeloulz@yahoo.com;2mountassir27@yahoo.fr;3belghaba@yahoo.fr

**Article History**: Received**24**October**2017**; Accepted**17**December**2017** c2017 MJM.

**Contents**

**1** **Introduction. . . 53**

**2** **Preliminaries. . . 54**

**3** **Analysis of the Method. . . 55**

**4** **Applications. . . 56**

**5** **Conclusion. . . 59**

**References. . . 59**

**1. Introduction**

Systems of partial differential equations have attracted much attention in a variety of applied sciences. The general ideas and the essential features of these systems are of wide ap-plicability. These systems were formally derived to describe wave propagation, to control the shallow water waves, and to examine the chemical reaction-diffusion model of Brusselator [1]. To solve these equations or systems, researchers use many methods, among them, we find an Adomian decomposition method (ADM) [2], homotopy perturbation method (HPM) [3], variational iteration method (VIM) [4], Fourier transform method [5], Fourier series method [6], Laplace transform method [7], and Sumudu transform method [8], and then ex-tended it to solve differential equations of fractional orders. Recently, there appeared a large part of scientific research

concerning local fractional differential equations or local frac-tional partial differential, adopted in its entirety on the above mentioned methods to solve this new types of equations. For example, among these research we find, local fractional Ado-mian decomposition method ([9], [10], [15]), local fractional homotopy perturbation method ([11], [12]), local fractional homotopy perturbation Sumudu transform method [13], local fractional variational iteration method ([14], [15]), local frac-tional variafrac-tional iteration transform method ([16]-[18]), local fractional Fourier series method ([19]-[21]), Laplace trans-form series expansion method [22], local fractional Sumudu transform method ([23], [24]), local fractional Sumudu trans-form series expansion method ([25], [26]), local fractional Sumudu decomposition method for linear partial differential equations with local fractional derivative [27].

The basic motivation of the present study is to extend the application of the local fractional Sumudu decomposition method suggested by D. Ziane et al.[27] to solve linear system of local fractional partial differential equations. The advantage of this method is its ability to combine two powerful methods to obtain exact solutions for linear system of local fractional partial differential equations. Three examples are given to re-confirm the effectiveness of this method.

In section 3 We present an analysis of the proposed method. In section 4 We apply the modified method (LFSDM) to solve the proposed systems. Finally, the conclusion follows.

**2. Preliminaries**

In this section, we present the basic theory of local fractional calculus and we focus specifically on the definitions of the fol-lowing concepts: Local fractional derivative, local fractional integral, some important results and local fractional Sumudu transform.

Definition 2.1. The local fractional derivative of Ψ(r)of orderηat r=r0is defined ([28],[29])

Ψ(η)(r) = d

η_{Φ}

drη

_{r}_{=}_{r}

0

=∆

η_{(}_{Ψ}_{(}_{r}_{)}_{−}_{Ψ}_{(}_{r}

0))

(r−r0)η

, (2.1)

where

∆η(Ψ(r)−Ψ(r0))∼=Γ(1+η) [(Ψ(r)−Ψ(r0))]. (2.2)

For any r∈(α,β), there exists

Ψ(η)(r) =Dη_{r}Ψ(r),

denoted by

Ψ(r)∈Dη

r(α,β).

Local fractional derivative of high order is written in the form

Ψ(mη)(r) =

m times

z }| {

Dr(η)· · ·Dr(η)Ψ(r), (2.3)

and local fractional partial derivative of high orderln 3

∂mηΨ(r)

∂rmη =

m times

z }| {

∂η

∂rη· · · ∂η

∂rηΨ(r). (2.4)

Definition 2.2. The local fractional integral ofΨ(r)of order

ηin the interval[α,β]is defined as ([28],[29])

αI

(η)

β Ψ(r) =

1

Γ(1+η)

Z β

α

Ψ(s)(ds)η

= 1

Γ(1+η)∆lims−→0

N−1

### ∑

i=0

f(si)(∆si)η,(2.5)

where∆si=si+1−si,∆s=max{∆s0,∆s1,∆s2,· · · }and

[si,si+1],s0=α,sN=β,is a partition of

the interval[α,β].For any r∈(α,β), there exists

αI

(η)

r Ψ(r),

denoted by

Ψ(r)∈Ir(η)(α,β).

Definition 2.3. In fractal space, the Mittage Leffler function, sine function and cosine function are defined as ([28],[29])

Eη(rη) =

+∞

### ∑

m=0 rmη

Γ(1+mη), 0<η61, (2.6)

sinη(r
η_{) =}

+∞

### ∑

m=0

(−1)η r

(2m+1)η

Γ(1+ (2m+1)η), 0<η61, (2.7)

cosη(rη) =

+∞

### ∑

m=0

(−1)η r

2mη

Γ(1+2mη),0<η61, (2.8)

The properties of local fractional derivatives and integral of nondifferentiable functions are given by ([28],[29])

dη

drη

rmη

Γ(1+mη)=

r(m−1)η

Γ(1+ (m−1)η). (2.9)

dη

drηEη(r
η_{) =}_{E}

η(rη). (2.10)

dη

drηsinη(r

η_{) =}_{cos}
η(r

η_{)}_{.} _{(2.11)}

dη

drηcosη(r

η_{) =}_{−sin}
η(r

η_{)}_{.}

dη

drηsinhη(r

η_{) =}_{cosh}

η(rη). (2.12)

dη

drηcoshη(r

η_{) =}_{sinh}

η(rη). (2.13)

Definition 2.4. [30] The local fractional Sumudu transform of Ψ(r)of orderηis defined as

LFSη{Ψ(r)} = zη(u),0<η61 (2.14)

= 1

Γ(1+η) Z ∞

0

Eη(−u

−η_{r}η_{)}Ψ(r)

uη (dr) η

Following (2.14), its inverse formula is defined as

LFS−_{η}1

Theorem 2.5. (1) (local fractional Sumudu transform of local fractional derivative). If LFSη{Ψ(r)}=zη(u),then one

has

LFSη

_{d}η

Ψ(r)

drη

=zη(u)−z(0)

uη . (2.16)

As the direct result of (2.16), we have the following results. If LFSη{Ψ(r)}=zη(u), we obtain

LFSη

_{d}nη

Ψ(r)

drnη

= 1

unη

"

zη(u)−

n−1

### ∑

k=0 ukη

Ψ(kη)(0) #

.

(2.17)

When n=2, from (2.17), we get

LFSη

d2η_{Ψ}_{(}_{r}_{)}

dr2η

= 1

u2η

h

zη(u)−Ψ(0)−uηΨ(η)(0)

i .

(2.18)

(2) (local fractional Sumudu transform of local fractional integral). If LFSη{Ψ(r)}=zη(u),then we have

LFSη

n

0Ir(η)Ψ(r)o=uη

zη(u). (2.19)

**3. Analysis of the Method**

To illustrate the basic idea of this method, we consider a general linear operator with local fractional derivative

(

∂ηV

∂sη +

∂ηW

∂rη +R1(V,W) =f(r,s),

∂ηW

∂sη +

∂ηV

∂rη +R2(V,W) =g(r,s),

(3.1)

where ∂η

∂(·)η denotes linear local fractional derivative

op-erator of orderη,R1,R2are the linear operators,and f(r,s), g(r,s)are the nondifferentiable source terms.

Taking the local fractional Sumudu transform (denoted in this paper byLFSη) on both sides of (3.1), we get

LFSη

h

∂ηV

∂sη

i

+ LFSη

h

∂ηW

∂rη

i

+LFSη[R1(V,W)] = LFSη[f(r,s)]

LFSη

h

∂ηW

∂sη

i

+ LFSη

h

∂ηV

∂rη

i

+LFSη[R2(V,W)] = LFSη[g(r,s)]

(3.2)

Using the property of the local fractional Sumudu trans-form, we have

LFSη[V(r,s)] =V(r,0) +uη(LFSη[f(r,s)])

−uη_{LFS}
η

h

∂ηW

∂rη +R1(V,W)

i

LFSη[W(r,s)] =W(r,0) +uη(LFSη[g(r,s)])

−uη_{LFS}
η

h

∂ηV

∂rη +R2(V,W)

i

(3.3)

Taking the inverse local fractional Sumudu transform on both sides of (3.3), gives

V(r,s) =V(r,0) +LFS−_{η}1(uη_{(}_{LFS}

η[f(r,s)]))

−LFS−_{η}1uη_{LFS}
η

h

∂ηW

∂rη +R1(V,W)

i

W(r,s) =W(r,0) +LFS−1

η (u
η_{(}_{LFS}

η[g(r,s)]))

−LFS−_{η}1

uη_{LFS}
η

h

∂ηV

∂rη +R2(V,W)

i

(3.4)

According to the Adomian decomposition method [2], we decompose the two unknown functionsV andW as an infinite series given by

V(r,s) =∑∞n=0Vn(r,s)

W(r,s) =∑∞n=0Wn(r,s)

. (3.5)

Substituting (3.5) in (3.4), we get

V(r,s) =V(r,0) + LFS−_{η}1(uη_{(}_{LFS}

η[f(r,s)]))

−LFS−_{η}1

uη_{LFS}
η

h

∂η ∂rη(∑

∞

n=0Wn) +R1(∑∞n=0Vn,∑∞n=0Wn)

i

W(r,s) =W(r,0) +LFS−_{η}1(uη_{(}_{LFS}

η[g(r,s)]))

−LFS−_{η}1uη_{LFS}
η

h

∂η ∂rη (∑

∞

n=0Vn) +R2(∑∞n=0Vn,∑∞n=0Wn)

i

(3.6)

On comparing both sides of (3.6), we have

V0(r,s) = V(r,0) + LFS−η1(u

η_{LFS}

η[f(r,s)]),

V1(r,s) = −LFS−η1

uη

LFSη

∂ηW0

∂rη +R1(V0,W0)

, (3.7)

V2(r,s) = −LFS−η1

uη

LFSη

∂ηW1

∂rη +R1(V1,W1)

,

V3(r,s) = −LFS−η1

uη

LFSη

∂ηW2

∂rη +R1(V2,W2)

,

.. .

and

W0 = W(r,0) + LFS−η1(u

η_{LFS}

η[g(r,s)]),

W1 = −LFS−η1

uη

LFSη

∂ηV0

∂rη +R2(V0,W0)

, (3.8)

W2 = −LFS−η1

uη

LFSη

∂ηV1

∂rη

+R2(V1,W1)

,

W3 = −LFS−η1

uη

LFSη

∂ηV2

∂rη +R2(V2,W2)

,

.. .

Finally, we approximate the analytical nondifferentiable solution(V,W)of the system (3.1) by

V(r,s) =limN→∞∑Nn=0Vn(x,t)

W(r,s) =limN→∞∑Nn=0Wn(x,t)

**4. Applications**

In this section, we will implement the proposed method lo-cal fractional Sumudu decomposition method (LFSDM) for solving some exemples.

Example 4.1. First, we consider the homogeneous linear system of local fractional partial differential equations

(

∂ηU

∂sη −

∂ηV

∂rη +U+V =0

∂ηV

∂sη −

∂ηU

∂rη +U+V =0

,0<η61, (4.1)

with initial conditions

U(r,0) =sinhη(r

η_{)}_{,}_{V}_{(}_{r}_{,}_{0}_{) =}_{cosh}
η(r

η_{)}_{.} _{(4.2)}

Taking the local fractional Sumudu transform on both sides of each equation of the system (4.1), we have

LFSη[U(r,s)] =U(r,0)

−uη_{LFS}
η

h

−∂ηV(r,s)

∂rη +U(r,s) +V(r,s)

i

LFSη[V(r,s)] =V(r,0)

−uη_{LFS}
η

h

−∂ηU(r,s)

∂rη +U(r,s) +V(r,s)

i (4.3)

Taking the inverse local fractional Sumudu transform on both sides of each equation of the system (4.3) subject to the initial conditions (4.2), we obten

U(r,s) =sinhη(rη)

−LFS−_{η}1uη_{LFS}
η

h

−∂ηV(r,s)

∂rη +U(r,s) +V(r,s)

i

V(r,s) =coshη(rη)

−LFS−_{η}1uη_{LFS}
η

h

−∂ηU(r,s)

∂rη +U(r,s) +V(r,s)

i

(4.4)

According to the Adomian decomposition method [2], we decompose the unknown functions U and V as two infinite series given by

U(r,s) =∑∞n=0Un(r,s),

V(r,s) =∑∞n=0Vn(r,s).

(4.5)

Substituting (4.5) in (4.4), we get

∑∞n=0Un(r,s) =sinhη(rη)

−LFS−_{η}1

uη

LFSη

−∂η ∂rη (∑

∞

n=0Vn(r,s)) +∑∞n=0Un(r,s) +∑∞n=0Vn(r,s)

∑∞n=0Vn(r,s) =coshη(rη)

−LFS−_{η}1

uη

LFSη

−∂η ∂rη (∑

∞

n=0Un(r,s)) +∑∞n=0Un(r,s) +∑∞n=0Vn(r,s)

(4.6)

On comparing both sides of (4.6), we have

U0(r,s) =sinhη(rη),

U1(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηV0(r,s)

∂rη +U0(r,s) +V0(r,s) i

,

U2(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηV1(r,s)

∂rη +U1(r,s) +V1(r,s)

i ,

U3(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηV2(r,s)

∂rη +U2(r,s) +V2(r,s)

i ,

.. .

(4.7)

V0(r,s) =coshη(rη),

V1(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηU0(r,s)

∂rη +U0(r,s) +V0(r,s) i

,

V2(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηU1(r,s)

∂rη +U1(r,s) +V1(r,s)

i ,

V3(r,s) =−LFS−η1

uη_{LFS}
η

h

−∂ηU2(r,s)

∂rη +U1(r,s) +V2(r,s)

i ,

.. .

(4.8)

and so on.

From the equations (4.7)-(4.8), the first solution terms of local fractional sumudu decomposition method of the system (4.1), is given by

U0(r,s) =sinhη(rη),

U1(r,s) =−coshη(rη) s

η Γ(1+η),

U2(r,s) =sinhη(rη) s

2η Γ(1+2η), U3(r,s) =−coshη(rη) s

3η Γ(1+3η), ..

.

(4.9)

and

V0(r,s) =coshη(rη),

V1(r,s) =−sinhη(rη) s

η Γ(1+η), V2(r,s) =coshη(rη) s

2η Γ(1+2η), V3(r,s) =−sinhη(rη) s

3η Γ(1+3η), ..

.

(4.10)

Then the local fractional solution(U,V)in series form is given by

U(r,s) =sinhη(rη)(1+ s

2η

Γ(1+2η)+· · ·)

−coshη(rη)( s

η Γ(1+η)+

s3η

Γ(1+3η)+· · ·), V(r,s) =coshη(rη)(1+ s

2η

Γ(1+2η)+· · ·)

−sinhη(rη)( s

η Γ(1+η)+

s3η

Γ(1+3η)+· · ·),

and the solution(U,V)in the close form is

U(r,s) =sinhη(rη−sη).

V(r,s) =coshη(rη−sη).

(4.12)

Substitutingη=1into (4.12), we obtain

U(r,s) =sinh(r−s).

V(r,s) =cosh(r−s). (4.13)

This obtained result is the same as in the article [31] in the caseα=β=1,as well as the same result presented in the article [32] in the same case.

Example 4.2. Second, we consider the nonhomogeneous lin-ear system of local fractional partial differential equations

(

∂ηU

∂sη −

∂ηV

∂rη −U+V =−2

∂ηV

∂sη +

∂ηU

∂rη −U+V =−2

,0<η61, (4.14)

subject to the initial conditions

U(r,0) =1+Eη(rη),V(r,0) =−1+Eη(rη). (4.15)

Taking the local fractional Sumudu transform on both sides of each equation of the system (4.14), we have

LFSη[U(r,s)] =U(r,0)−2uη

+uη_{LFS}
η

h

∂ηV(r,s)

∂rη +U(r,s)−V(r,s)

i

LFSη[V(r,s)] =V(r,0)−2uη

+uη_{LFS}
η

h

−∂ηU(r,s)

∂rη +U(r,s)−V(r,s)

i

(4.16)

Taking the inverse local fractional Sumudu transform on both sides of each equation of the system (4.16) subject to the initial conditions (4.15), we obtain

U(r,s) =1+Eη(rη)−2 s

η Γ(1+η)

+LFS−_{η}1uη_{LFS}
η

h

∂ηV(r,s)

∂rη +U(r,s)−V(r,s)

i

V(r,s) =−1+Eη(rη)−2 s

η Γ(1+η)

+LFS−1

η

uη_{LFS}
η

h

−∂η_{U}_{(}_{r}_{,}_{s}_{)}

∂rη +U(r,s)−V(r,s)

i

(4.17)

According to the Adomian decomposition method [2], we decompose the unknown functions U and V as two infinite series given by

U(r,s) =∑∞n=0Un(r,s),

V(r,s) =∑∞n=0Vn(r,s).

(4.18)

Substituting (4.18) in (4.17), we get

∑∞n=0Un(r,s) =1+Eη(rη)−2 s

η Γ(1+η)

+LFS−_{η}1uη_{LFS}
η

h

∂η ∂rη(∑

∞

n=0Vn) +∑∞n=0Un−∑∞n=0Vn

i

∑∞n=0Vn(r,s) =−1+Eη(rη)−2 s

η Γ(1+η)

+LFS−_{η}1uη_{LFS}
η

h −∂η

∂rη (∑ ∞

n=0Un) +∑∞n=0Un−∑∞n=0Vn

i

(4.19)

On comparing both sides of (4.19), we have

U0(r,s) =1+Eη(rη)−2 s

η Γ(1+η),

U1(r,s) = LFS−η1

uη_{LFS}
η

h

∂ηV0(r,s)

∂rη +U0(r,s)−V0(r,s)

i ,

U2(r,s) =LFS−η1

uη_{LFS}
η

h

∂ηV1(r,s)

∂rη +U1(r,s)−V1(r,s)

i ,

U3(r,s) =LFS−η1

uη_{LFS}
η

h

∂ηV2(r,s)

∂rη +U2(r,s)−V2(r,s) i

,

.. .

(4.20)

V0(r,s) =−1+Eη(rη)−2 s

η Γ(1+η), V1(r,s) =LFS−η1

uη_{LFS}
η

h

−∂ηU0(r,s)

∂rη +U0(r,s)−V0(r,s)

i ,

V2(r,s) =LFS−η1

uη_{LFS}
η

h

−∂ηU1(r,s)

∂rη +U1(r,s)−V1(r,s) i

,

V3(r,s) =LFS−η1

uη_{LFS}
η

h

−∂ηU2(r,s)

∂rη +U2(r,s)−V2(r,s)

i ,

.. .

(4.21)

and so on.

From the equations (4.20)-(4.21), the first solution terms of local fractional sumudu decomposition method of the system (4.14), is given by

U0(r,s) =1+Eη(rη)−2 s

η Γ(1+η),

U1(r,s) =Eη(rη) s

η Γ(1+η)+2

sη Γ(1+η), U2(r,s) =Eη(rη) s

2η Γ(1+2η), U3(r,s) =Eη(rη) s

3η Γ(1+3η), ..

.

(4.22)

and

V0(r,s) =−1+Eη(rη)−2 s

η Γ(1+η), V1(r,s) =−Eη(rη) s

η Γ(1+η)+2

sη Γ(1+η), V2(r,s) =Eη(rη) s

2η Γ(1+2η),

V3(r,s) =−Eη(rη) s

3η Γ(1+3η), ..

.

Then the local fractional solution(U,V)in series form is given by

U(r,s) =1+Eη(rη)(1+ s

η Γ(1+η)+

s2η Γ(1+2η)+

s3η

Γ(1+3η)+· · ·), V(r,s) =−1+Eη(rη)(1− s

η Γ(1+η)+

s2η

Γ(1+2η)−

s3η

Γ(1+3η)+· · ·),

(4.24)

and the solution(U,V)in the close form is

U(r,s) =1+Eη((r+s)η).

V(r,s) =−1+Eη((r−s)η).

(4.25)

Substitutingη=1into (4.25), we obtain

U(r,s) =1+er+s.

V(r,s) =−1+er−s. (4.26)

This obtained result is the same as in the article [1],as well as the same work presented in [33].

Example 4.3. Finaly, we consider the homogeneous linear system of local fractional partial differential equations

∂ηU

∂tη +

∂ηV

∂rη −

∂ηW

∂sη =W

∂ηV

∂tη +

∂ηW

∂rη +

∂ηU

∂sη =U

∂ηW

∂tη +

∂ηV

∂rη −

∂ηV

∂rη =V

,0<η61, (4.27)

subject to the initial conditions

U(r,s,0) =sinη((r+s)η),

V(r,s,0) =cosη((r+s)η),

W(r,s,0) =−sinη((r+s)η).

(4.28)

Taking the local fractional Sumudu transform on both sides of each equation of the system (4.27), we have

LFSη[U(r,s,t)] =U(r,s,0)

+uη_{LFS}
η

h

−∂ηV(r,s,t)

∂rη +

∂ηW(r,s,t)

∂sη +W(r,s,t)

i

LFSη[V(r,s,t)] =V(r,s,0)

+uη_{LFS}
η

h

−∂ηW(r,s,t)

∂rη −

∂ηU(r,s,t)

∂sη +U(r,s,t)

i

LFSη[W(r,s,t)] =W(r,s,0)

+uη_{LFS}
η

h

−∂ηV(r,s,t)

∂rη +

∂ηV(r,s,t)

∂sη +V(r,s,t)

i

(4.29)

Taking the inverse local fractional Sumudu transform on both sides of each equation of the system (4.29) subject to the

initial conditions (4.28), we obtain

U(r,s,t) =sinη((r+s)η)

+LFS−_{η}1

uη_{LFS}
η

h

−∂ηV(r,s,t)

∂rη +

∂ηW(r,s,t)

∂sη +W(r,s,t)

i

V(r,s,t) =cosη((r+s)η)

+LFS−_{η}1uη_{LFS}
η

h

−∂ηW(r,s,t)

∂rη −

∂ηU(r,s,t)

∂sη +U(r,s,t)

i

W(r,s,t) =−sinη((r+s)η)

+LFS−_{η}1uη_{LFS}
η

h

−∂ηV(r,s,t)

∂rη +

∂ηV(r,s,t)

∂sη +V(r,s,t)

i

(4.30)

According to the Adomian decomposition method [2], we decompose the unknown functions U and V as two infinite series given by

U(r,s,t) =∑∞n=0Un(r,s,t),

V(r,s,t) =∑∞n=0Vn(r,s,t),

W(r,s,t) =∑∞n=0Wn(r,s,t),

(4.31)

Substituting (4.31) in (4.30), we get

∑∞n=0Un(r,s,t) =sinη((r+s)η)

+LFS−_{η}1

uη_{LFS}
η

h −∂η

∂rη(∑ ∞

n=0Vn) + ∂

η

∂sη(∑ ∞

n=0Wn) +∑∞n=0Wn

i

∑∞n=0Vn(r,s,t) =cosη((r+s)η)

+LFS−_{η}1uη_{LFS}
η

h −∂η

∂rη (∑ ∞

n=0Wn)− ∂

η

∂sη(∑ ∞

n=0Un) +∑∞n=0Un

i

∑∞n=0Vn(r,s,t) =−sinη((r+s)η)

+LFS−_{η}1uη_{LFS}
η

h −∂η

∂rη(∑ ∞

n=0Vn) + ∂

η

∂sη (∑ ∞

n=0Vn) +∑∞n=0Vn

i

(4.32)

On comparing both sides of (4.32), we have

U0=sinη((r+s)η),

U1= LFS−η1

uη_{LFS}
η

h −∂ηV0

∂rη +

∂ηW0

∂sη +W0

i ,

U2=LFS−η1

uη_{LFS}
η

h −∂ηV1

∂rη +

∂ηW1

∂sη +W1 i

,

U3=LFS−η1

uη_{LFS}
η

h −∂ηV2

∂rη +

∂ηW2

∂sη +W2

i ,

.. .

(4.33)

V0=cosη((r+s)η),

V1=LFS−η1

uη_{LFS}
η

h −∂ηW0

∂rη −

∂ηU0

∂sη +U0

i ,

V2=LFS−η1

uη_{LFS}
η

h −∂ηW1

∂rη −

∂ηU1

∂sη +U1 i

,

V3=LFS−η1

uη_{LFS}
η

h −∂ηW2

∂rη −

∂ηU2

∂sη +U2

i ,

.. .

and

W0=−sinη((r+s)η),

W1=LFS−η1

uη_{LFS}
η

h −∂ηV0

∂rη +

∂ηV0

∂sη +V0

i ,

W2=LFS−η1

uη_{LFS}
η

h −∂ηV1

∂rη +

∂ηV1

∂sη +V1

i ,

W3=LFS−η1

uη_{LFS}
η

h −∂ηV2

∂rη +

∂ηV2

∂sη +V2

i ,

.. .

(4.35)

and so on.

From the equations (4.33)-(4.35), the first solution terms of local fractional sumudu decomposition method of the system (4.27), is given by

U0(r,s,t) =sinη((r+s)η),

U1(r,s,t) =−cosη((r+s)η) t

η Γ(1+η), U2(r,s,t) =−sinη((r+s)η) t

2η Γ(1+2η), U3(r,s,t) =cosη((r+s)η) t

3η Γ(1+3η), U4(r,s,t) =sinη((r+s)η) t

4η Γ(1+4η), ..

.

(4.36)

V0(r,s,t) =cosη((r+s)η),

V1(r,s,t) =sinη((r+s)η) t

η Γ(1+η), V2(r,s,t) =−cosη((r+s)η) t

2η Γ(1+2η),

V3(r,s,t) =−sinη((r+s)η) t

3η Γ(1+3η), V4(r,s,t) =cosη((r+s)η) t

4η Γ(1+4η), ..

.

(4.37)

and

W0(r,s,t) =−sinη((r+s)η),

W1(r,s,t) =cosη((r+s)η) t

η Γ(1+η), W2(r,s,t) =sinη((r+s)η) t

2η Γ(1+2η), W3(r,s,t) =−cosη((r+s)η) t

3η Γ(1+3η), W4(r,s,t) =−sinη((r+s)η) t

4η Γ(1+4η),

.. .

(4.38)

Then, the local fractional solution(U,V,W)in series form, is given by

U(r,s,t) =sinη((r+s)η)(1− t

2η Γ(1+2η)+

t4η

Γ(1+4η)+· · ·)

−cosη((r+s)η)( t

η Γ(1+η)−

t3η

Γ(1+3η)+· · ·), V(r,s,t) =cosη((r+s)η)(1− s

2η Γ(1+2η)+

s4η

Γ(1+4η)+· · ·)

+sinη((r+s)η)( t

η Γ(1+η)−

t3η

Γ(1+3η)+· · ·), W(r,s,t) =−sinη((r+s)η)(1− t

2η Γ(1+2η)+

t4η

Γ(1+4η)+· · ·)

+cosη((r+s)η)( t

η Γ(1+η)−

t3η

Γ(1+3η)+· · ·),

(4.39)

and the solution(U,V,W)in the close form is

U(r,s,t) =sinη((r+s−t)η).

V(r,s,t) =cosη((r+s−t)η).

W(r,s,t) =−sinη((r+s−t)η).

(4.40)

In the case ofη=1,we get

U(r,s,t) =sin(r+s−t).

V(r,s,t) =cos(r+s−t).

W(r,s,t) =−sin(r+s−t).

(4.41)

This result is the exact solution of the system (4.27) in the case ofη=1

**5. Conclusion**

In this work, we have seen that the composite method of Ado-mian decomposition method and Sumudu transform method in the sense of local fractional derivative, proved very effective to solve linear systems of local fractional partial differen-tial equations. The local fractional Sumudu decomposition method (LFSDM) is suitable for such problems and is very user friendly. The advantage of this method is its ability to combine two powerful methods for obtaining exact solutions of linear systems of local fractional partial differential equa-tions. The results obtained in the examples presented, showed that this method is capable of solving other problems of these types.

**References**

[1] _{M. Khana, M. A. Gondala and S. K. Vanani,} _{On the}

Coupling of Homotopy Perturbation and Laplace Trans-formation for System of Partial Differential Equations,

Appl. Math. Sci., 6(10)(2012), 467-478.

[2] _{G. Adomian and R. Rach,}_{Equality of partial solutions in}

the decomposition method for linear or nonlinear partial differential equations, Comput. Math. Appl., 10(1990), 9-12.

[3] _{J. H. He,}_{”Homotopy perturbation technique”}_{, Comput.}

Meth. Appl. Mech. Eng., 178(1999), 257-262.

[4] _{J. H. He,}_{”A new approach to nonlinear partial }

differen-tial equations”, Comm. Nonlinear. Sci. Numer. Simul., 2(1997), 203-205.

[5] _{V. Namias,}_{The Fractional Order Fourier Transform and}

its Application to Quantum Mechanics, IMA. J. Appl. Math., 25(3)(1980), 241-265.

[6] _{N. H. ASMAR,} _{Partial Differential Equations with}

Fourier Series and Boundary Value Problems, Univer-sity of Missouri Columbia, Missouri 65211.

[7] _{I. Podlubny,}_{The Laplace Transform Method for Linear}

[8] _{A. Kilic¸man and H. Eltayeb,}_{On a New Integral }

Trans-form and Differential Equations, Math. Problems in Eng., A. ID463579(2010), 13 pp.

[9] _{S. P. Yan, H. Jafari and H. K. Jassim,}_{Local Fractional}

Adomian Decomposition and Function Decomposition Methods for Laplace Equation within Local Fractional Operators,Adv. in Math. Phys., A. ID 161580(2014), 7 pp.

[10] _{X. J. Yang, D. Baleanu and W. P. Zhong,} _{}

Approxi-mate Solutions for Diffusion Equations on Cantor Space-Tame, Proceedings of the Romanian Academy, Series A., 14(2)(2013), 127-133.

[11] _{X. J. Yang, H. M. Srivastava and C. Cattani,}_{Local }

Frac-tional Homotopy Perturbation Method for Solving Fractal Partial Differential Equations Arising in Mathematical Physics, Romanian Repo. in Phys., 67(3)(2015), 752-761.

[12] _{Y. Zhang, C. Cattani and X. J. Yang,} _{Local }

Frac-tional Homotopy Perturbation Method for Solving Non-Homogeneous Heat Conduction Equations in Fractal Do-mains, Entropy., 17(2015), 6753-6764.

[13] _{D. Kumar, J. Singh, H. M. Baskonus and H. Bulut,}_{An}

effective computational approach to local fractional tele-graph equations, Nonlinear Sci. Lett. A., 8(2)(2017), 200-206.

[14] _{X. J. Yang, D. Baleanu, Y. Khan and S. T. }

Mohyud-din,Local Fractional Variational Iteration Method for Diffusion and Wave Equation on Cantor Sets, Rom. J. Phys., 59(1-2)(2014), 36-48.

[15] _{D. Baleanu, J. A. T. Machado, C. Cattani, M. C. Baleanu}

and X. J. Yang,Local Fractional Variational Iteration and Decomposition Methods for Wave Equation on Can-tor Sets within Local Fractional OperaCan-tors,Abst. Appl. Anal., A. ID 535048(2014), 6 pp.

[16] _{C. F. Liu, S. S. Kong and S. J. Yuan,} _{Reconstructive}

Schemes for Variational Iteration Method within Yang-Laplace Transform with Application to Heat Conduction Problem,Thermal Science., 17(3)(2013), 715-721.

[17] _{A. M. Yang, J. Li, H. M. Srivastava, G. N. Xie and X.}

J. Yang,Local Fractional Laplace Variational Iteration Method for Solving Linear Partial Differential Equations with Local Fractional Derivative, Dis. in Nat. and Soc., A. ID 365981(2014), 8 pp.

[18] _{Y. J. Yang and L. Q. Hua,}_{Variational Iteration }

Trans-form Method for Fractional Differential Equations with Local Fractional Derivative, Abst. and Appl. Anal., A. ID 760957(2014), 9 pp.

[19] _{Y. J. Yang, D. Baleanu and X. J. Yang,}_{Analysis of }

Frac-tal Wave Equations by Local Fractional Fourier Series Method, Adv. in Math. Phys., A. ID 632309(2013), 6 pp.

[20] _{M. S. Hu, R. P. Agarwal and X. J. Yang,}_{Local }

Frac-tional Fourier Series with Application to Wave Equation in Fractal Vibrating String, Abst. and Appl. Anal., A. ID 567401(2012), 15 pp.

[21] _{Z. Y. Chen, C. Cattani and W. P. Zhong,}_{Signal Processing}

for Nondifferentiable Data Defined on Cantor Sets: A

Local Fractional Fourier Series Approach, Adv. in Math. Phys., A. ID 561434(2011), 7 pp.

[22] _{H. Sun and X. H. Liu,} _{Laplace Transform Series }

Ex-pansion Method for Solving the Local Fractional Heat-Transfer Equation Defind on Cantor Sets,Thermal Sci-ence., 20(3)(2017), 777-780.

[23] _{H. M. Srivastava, A. K. Golmankhaneh, D. Baleanu and}

X. J. Yang,Local Fractional Sumudu Transform with Ap-plication to IVPs on Cantor Sets,Abst. and Appl. Anal., A. ID 620529(2014), 7 pp.

[24] _{Y. Wang, X. X. Lu, C. Cattani, J. L. G. Guirao and X.}

J. Yang,Solving Fractal Stedy Heat-Transfer Problems with the Local Fractional Sumudu Transform,Thermal Science., 19(2)(2015), 637-641.

[25] _{A. M. Yang, J. Lia, Y. Z. Zhang and W. X. Liu,} _{A}

New Coupling Shedule for Series Expansion Method and Sumudu Transform with an Applications to Diffu-sion Equation in Fractal Heat-Transfer,Thermal Science., 19(1)(2015), 145-149.

[26] _{Z. H. Guo, O. Acan and S. Kumar,}_{Sumudu Transform }

Se-ries Expansion Method for Solving the Local Fractional Laplace Equation in Fractal Thermal Problems,Thermal Science., 20(3)(2016), 739-742.

[27] _{D. Ziane, D. Baleanu, K. Belghaba and M. Hamdi}

Cherif,Local fractional Sumudu decomposition method for linear partial differential equations with lo-cal fractional derivative, J. of K. Saud Univ-Sci., http://dx.doi.org/10.1016/j.jksus.2017.05.002, 2017.

[28] _{X. J. Yang,}_{Fractional Functional Analysis and Its }

Appli-cations, Asian Academic, Hong Kong, 2011.

[29] _{X. J. Yang,}_{Local Fractional Calculus and Its }

Applica-tions, World Science Publisher, New York, NY, USA, 2012.

[30] _{H. M. Srivastava, A. K. Golmankhaneh, D. Baleanu and}

X. J. Yang, Local Fractional Sumudu Transform with Application to IVPs on Cantor Sets, Abs. and Appl. Anal., A. ID 176395 (2014), 7 pp.

[31] _{H. Jafari, M. Nazari, D. Baleanu and C. M. Khalique,}_{A}

new approach for solving a system of fractional partial differential equations, Comput. and Math. with Appl., 66(2013), 838-843.

[32] _{V. Parthiban and K. Balachandran,}_{Solutions of System}

of Fractional Partial Differential Equations,Appli. and Appl. Math., 8(1)(2013), 289-304.

[33] _{M. S. H. Chowdhury, I. Hashim and A. F. Ismail,}_{}

Analyti-cal Treatment of System of Linear and Nonlinear PDEs by Homotopy-Perturbation Method,Proceedings of the World Congress on Engineering, London, U.K, Vol III, June 30 - July 2, 2010.

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